This invention relates generally to self-contained underwater breathing apparatus, and more particularly concerns devices for reducing the physical effort required to use an open circuit, two-stage demand underwater breathing device in an underwater environment.
The use of self-contained underwater breathing apparatus . A flexible hose leads from the first stage valve to another pressure-sensitive valve (called a second-stage regulator) carried by the driver's mouth. By alternately inhaling air through the valve from the hose, and exhaling through the valve to the surrounding water, the diver can breath under water for long periods of time. Designs for second stage regulators are shown in U.S. Pat. Nos. 3,633,611 and 4,010,746 and in others. The mechanics of valve operation have seemed to require the diver to exert at least a small amount of positive, usually conscious effort to inhale and exhale through the second stage regulator. This breathing effort results in diver lung fatigue and loss of diver efficiency.
It is accordingly the general object of the present invention to provide a breathing effort reduction device for use with the air delivery regulator of an open circuit self-contained underwater demand breathing apparatus. A related object is to offer such a device which provides this breathing effort reduction when the diver is in the most common diver body orientations or positions, and which does not adversely affect diver breathing efforts when the diver is in the other body orientations or positions.
Another object is to provide a diver breathing effort reduction device which operates effectively at various water depths and at various breathing rates, yet which does not reduce diver comfort.
Another object is to provide a breathing effort reduction device which is in inexpensive to manufacture and reliable and rugged in operation.
Yet another object is to provide a breathing effort reduction device which, in its various embodiments, can be used with any commercially available scuba regulator.